When it comes to choosing the right fin for your surfboard, there are a lot of factors at play. Sifting through the ocean of information about surfboard fin design, one can get lost pretty easily. With a plethora of different shapes, sizes, materials and setups - not knowing the basics of fin design can make the task of choosing a fin feel monumental. This guide is designed to equip you with the information you’ll need to choose the right fin for your board and find the surfing experience you're after.
To understand what makes a certain fin unique, it is necessary to understand the whole picture. From conception to production, each step of creating a fin affects the wave-riding experience. My idea is to share my experience and knowledge so that anyone can access information that can help them find the wave riding experience they are seeking.
FIN PRODUCTION
There are many methods of production for creating surfboard fins. Full fibreglass fins, moulded fibreglass fins, carbon fins, plastic fins, wooden fins - the list goes on.
All GFYFC fins are made from fibreglass panels. Each panel is made by using 40 layers of 6oz cloth saturated with resin one single layer at a time, ensuring that the right cloth-to-resin ratio is achieved so that the desired flex attributes of the panel are present. Pigments are mixed into the resin to create the desired colour (think mixing paints).
Once the panel is finished it will need to cure until it is hard enough to remove from the flat surface it was laid on. The panels are then cut out using various methods. CNC’s, bandsaws, jigsaws and just about any other tool that is strong enough to cut these fibreglass panels can be used. At this stage, the bases of the fins will be cut to fit the appropriate fin system (FCS, Futures, single fin Bahne box, etc).
From there the fins are meticulously foiled (shaped) to make the fin more hydrodynamic by creating an even and clean curve across the entirety of the fin. This is a very important part of the process as it enhances or limits the potential performance of a template. Flex is also created and fine-tuned during this process.
Once the fin is foiled, it gets sanded using various grits of sandpaper to achieve the desired finish. And then voilà, the fin is complete and ready to go.
Watch these short videos on the various parts of the process:
FIN SETUPS AND HOW TO CHOOSE THE RIGHT FIN
There are a few major factors to consider when selecting a fin. Depending on the size and design of the surfboard, you will need to consider the size and design of the fin. Getting the sizing and template right is essential to creating the experience you're after. A fin too big will feel draggy and sluggish, a fin too small will lack control and drive. The sweet spot is unique for every board and every style of surfing.
Choosing the right template is a bit more of an art than a science and largely depends on the user and the desired experience. In all fins, there are many variations in shape and each is unique in function. Like everything in surfboard design, there are trade-offs - what you make up for in one area you lose in another. The surf experience is entirely unique to the individual and what works for one person might not work for another. Be open-minded and figure out for yourself what ‘good surfing’ feels like, without the prejudice of what ‘good surfing’ is supposed to look like. Using your experience and knowledge of surfboard design, the aim is to find your sweet spot. Perhaps it’s as simple as trimming a knee-high runner at your local beach.
FIN SETUPS
There are a multitude of different fin setups available today. From single fins to thrusters to twinzers - almost any amount and configuration of fins seems possible. For the purpose of helping you to choose a fin, I’ve reduced the options to the main three setups GFYFC is known for.
Single Fins - one central fin, 50/50 foil.
Twin Fins - two fins set near the rails, flat foil, 80/20 foil, 50/50 foils.
2+1’s - one central single fin paired with two smaller side fins set near the rails.
SINGLE FINS
The pivot-fin, the all-rounder and the flex-fin are the three basic points on the sliding scale of single-fin design.
The pivot fin experience is associated with control, stability, tight radius turning and direct response - best paired with classic longboards and the associated style of surfing. These fins were the standard in the early days of single-fin longboarding, and have remained popular in contemporary classic longboarding. Generally pivot fins have an upright profile with increased surface area throughout the fin. This gives these fins the distinct feeling they are famous for.
On the other side of the scale are flex fins. These fins are usually raked-out tapered fins that flex at the tip. As the fin bends under the pressure exerted onto the fin during turns, the flexy tip bends, creating the delayed feeling of the board sinking into the arc of the turn. As the arc reaches its apex and the pressure relieves, the fin re-coils back into its original shape creating a spring feeling that propels the board forward. This is a feeling unique to fins that flex and the experience of flex-fin surfing includes playing with that delay. Once in tune with the delay from the flex and projection from the recoil, the surfer can pre-empt and exploit the movement of the board.
The all-rounder fin group is somewhere along the middle of the sliding scale. Characterised by their versatility, these fins adapt attributes from both pivot and flex fins. Some are more flex-oriented than others, some are more pivot-oriented than others. They’re predictable but still add a level of spice to the experience. What’s great about these fins is that they’re adaptable to many boards too, which means that as long as you’re in the right size range you should be good to go!
One easy way to get the right size range for your fin is to use the size of your board to estimate the size of the fin you’ll need. For example, a board in the 9’-9’5” range would do best with a fin that size in inches (i.e. 9”-9.5”). It’s not an exact science, but it is a useful tool to point you in the right direction.
TWIN FINS
In the early days of modern surfboard building (mid-1940s), Bob Simmons first designed boards with two fins on each rail. It wasn’t until the 70’s when the shortboard revolution was in full swing that twin fins really burst into popularity.
Twin fins are renowned for their speed and agility because of the reduced drag that is created by forces exerted onto the fins. In twin fin design, there are multiple factors at stake and not every twin fin setup works with every surfboard. Depending on factors like tail width, rail shape, bottom contours and several others, a particular fin will provide the ideal lift-to-drag ratio.
On the twin fin design scale, you have keel fins on one side, upright twin fins on the other side and a whole world of twin/keel designs (tweels) in between.
Keel fins have the most surface area and therefore have the most drag. This gives them their famous attributes of control and drive. It also gives them their infamous attribute of feeling rather ‘tracky’ compared to their upright counterpart. Keel fins go best on boards with wide tails like a classic fish. Down the line surfing and long drawn-out turns are the name of the game.
The upright twin is famously known for its loose, skatey feel. Generally, with a narrow base, the aim of this design is to free up the tail of the board, allowing movement when pushed through turns. These fins are best paired with more high-performance-oriented twin-fin designs that are made to be surfed vertically. Boards with inherent directional features like channel bottoms will do well with an upright twin too.
The twin/keel (tweel) falls into the middle ground. Not quite a keel, not quite an upright twin. These fins use attributes of both upright twins and keel fins to create a fin that does a little bit of everything. Some twin/keels look more like an upright twin fin, some look more like a keel fin. This middle-ground of design blends the control and drive of a keel fin with the loose, skatey feel of an upright twin.
2+1’s
The 2+1 design includes a central single fin that acts as a rudder with the addition of two side fins that are placed near the rails, creating control and drive when pushed through turns. The limiting attributes of a single fin are diminished with this design. 2+1 setups are designed to create a feeling that still encapsulates the essence of the single-fin experience but has the capability to draw contemporary lines on a wave. There are many directions to go with this design. Depending on the size ratio of the single fin to side fins, the board will either feel more like a single fin or more like a conventional thruster. Board design and desired experience are the main factors at play when deciding the size ratio of fins.
GLOSSARY / TERMINOLOGY
Template - the outline of the fin.
Rake - the measure of how much the fin ‘leans back’. The more the fin leans back, the more raked out it is. The more raked out a fin is the more it will tend to flex, the less rake a fin has (more upright) the more it will have a quick, direct response.
Foil - the surface’s shaped curve, usually with a thicker leading edge and a tapered trailing edge. A properly foiled fin is hydrodynamic and has improved performance capabilities. By reducing water resistance and increasing lift, the fin becomes more efficient in the water, feeling faster and more maneuverable. Foils come in many different shapes and ratios. These factors affect how the fin feels and in turn, affect the wave-riding experience.
Cant - refers to how many degrees away from perpendicular to the bottom of the surfboard the fin sits. For example, a fin with 6 degrees of cant will lean 6 degrees off perpendicular towards the rails of the board.
Flex - the amount the fin bends when pushed from the side. Careful foiling and specific material choice will not allow the fin to topple over but will flex on the horizontal plane (like a fish tail). The recoil the fin has refers to how quickly the fin returns back to its original upright position after being bent/flexed.
All in all, there is no specific science to choosing the correct fin, but I hope this helps you along on your journey. Enjoy the ride!
-Matt K
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